[Analytics Hub] Handle empty and error states

[ealeksandrov]

We should aim to handle network errors and empty data just like the My Store stats do, with an empty state message:

Each stats card should display its own empty state message, so if just one stats request fails, the other ones can still display data:

• Error state for failed order stats requests (Revenue, Orders, Products cards)
• Error state for failed top performers stats request (Products card)
• Error state for failed visitor stats request (Visitors & Views card)

For the scenario where the Date range acquisition fails, then we won't be able to trigger not a single stats request. For this scenario:

• We should pop out of the Analytics Hub back to the My Store view and display a notice about a critical error.